Gas furnaces in HVAC systems commonly employ a heat exchanger to transfer heat from a hot flow to a cold flow. In such furnaces, the hot flow is typically generated by igniting fuel to produce combustion products. The combustion products are then circulated through the heat exchanger. In contrast, the cold flow is produced by drawing air at ambient temperature into the gas furnace. The drawn air is then convectively forced across the heat exchanger. A temperature difference between the hot flow and the cold flow allows the heat exchanger to extract heat from the circulating combustion products and deposit such heat into a convection current of drawn air.
The figures described above are only exemplary and their illustration is not intended to assert or imply any limitation with regard to the environment, architecture, design, configuration, method, or process in which different embodiments may be implemented.